tailieunhanh - Mechanisms and Mechanical Devices Sourcebook

Motion control systems today can be found in such diverse applications as materials handling equipment, machine tool centers, chemical and pharmaceutical process lines, inspection stations, robots, and injection molding machines. Merits of Electric Systems Most motion control systems today are powered by electric motors rather than hydraulic or pneumatic motors or actuators because of the many benefits they offer: • More precise load or tool positioning, resulting in fewer product or process defects and lower material costs. • Quicker changeovers for higher flexibility and easier product customizing. • Increased throughput for higher efficiency and capacity. • Simpler system design for easier installation,. | _CHAPTER 1 MOTION control SYSTEMS MOTION CONTROL SYSTEMS OVERVIEW Fig. 1 This multiaxis X-Y-Z motion platform is an example of a motion control system. Motion control systems today can be found in such diverse applications as materials handling equipment machine tool centers chemical and pharmaceutical process lines inspection stations robots and injection molding machines. Merits of Electric Systems Most motion control systems today are powered by electric motors rather than hydraulic or pneumatic motors or actuators because of the many benefits they offer More precise load or tool positioning resulting in fewer product or process defects and lower material costs. Quicker changeovers for higher flexibility and easier product customizing. Increased throughput for higher efficiency and capacity. Simpler system design for easier installation programming and training. Lower downtime and maintenance costs. Cleaner quieter operation without oil or air leakage. Introduction A modern motion control system typically consists of a motion controller a motor drive or amplifier an electric motor and feedback sensors. The system might also contain other components such as one or more belt- ballscrew- or leadscrew-driven linear guides or axis stages. A motion controller today can be a standalone programmable controller a personal computer containing a motion control card or a programmable logic controller PLC . All of the components of a motion control system must work together seamlessly to perform their assigned functions. Their selection must be based on both engineering and economic considerations. Figure 1 illustrates a typical multiaxis X-Y-Z motion platform that includes the three linear axes required to move a load tool or end effector precisely through three degrees of freedom. With additional mechanical or electromechanical components on each axis rotation about the three axes can provide up to six degrees of freedom as shown in Fig. 2. Fig. 2 The .